test: print: Skip test on x86

These tests cannot work on x86 machines as memory at address zero is
not writable. Add a condition to skip these.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/test/print_ut.c b/test/print_ut.c
index b26f628..bb844d2 100644
--- a/test/print_ut.c
+++ b/test/print_ut.c
@@ -170,6 +170,10 @@
 	u8 *buf;
 	int i;
 
+	/* This test requires writable memory at zero */
+	if (IS_ENABLED(CONFIG_X86))
+		return -EAGAIN;
+
 	buf = map_sysmem(0, BUF_SIZE);
 	memset(buf, '\0', BUF_SIZE);
 	for (i = 0; i < 0x11; i++)
@@ -275,6 +279,10 @@
 	u8 *buf;
 	int i;
 
+	/* This test requires writable memory at zero */
+	if (IS_ENABLED(CONFIG_X86))
+		return -EAGAIN;
+
 	buf = map_sysmem(0, BUF_SIZE);
 	memset(buf, '\0', BUF_SIZE);
 	for (i = 0; i < 0x11; i++)